administration bldg plus locker room tied up in one system

administration bldg plus locker room tied up in one system

Hi
per my design scope , i have to supply make up air to the office, conference room, secretary plus i have to tie up locker and toilet area.
now exhaust for locker and toilet are is 850 cfm so i need that much make up air from vav system, which also serves the other administration area.
total 4000 cfm and total o.a 1525 cfm including the locker and toilet area.
i am using a gas fired rtu and vav boxes with hot water heating coils.

now my question is : 1) if i am using a separate exhaust for locker room and not taking return from that area going to rtu, wont my rtu which serves administration as well as locker area be shy on return air? how to solve this ?

2) to design vav box minimum/ max value: what are the parameters? if i design all boxes for 30% minimum than locker and toilet area wont have justice as it will not get 850 cfm of outside air but the 850 cfm of mixed air?

hope you all can help me solve the problem. and navigate through this..
thanks,

RE: administration bldg plus locker room tied up in one system

You can only return 10% of locker room air and none of the toilet room air. Put the toilet/locker rooms on a separate, constant volume 100% outside air (O/A) unit. If it is 3000 cfm or more the IECC will require energy recovery.

Put the other spaces on a separate unit (it can be VAV if you want).

Doing this will satisfy the code, and greatly simplify your project.

Read and get familiar with the International Mechanical Code.

Good luck.

RE: administration bldg plus locker room tied up in one system

Review the mechanical code like trash said, specifically the ventilation section. Code doesn't require outside air to toilet and locker rooms, only exhaust. If the rooftop unit supplies as much or more outside air than is exhausted, what's the problem? If it supplies less, then increase the outside air. Code is for a minimum required, not the absolute total required.

And remember, corridors can be used as make-up spaces, but not transfer plenums.

RE: administration bldg plus locker room tied up in one system

Put one on-off supply box for that, variable speed fan will take care of general supply pressure. Transition air is allowed, but it's not feasible with unpredictable VAV schedule and on-time of lockers that can differ from main area on-time.

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